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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e249a9d1c5f94cd1062aaaae7fc37f03dc3bc6662072aa57121640e67a483c3a' 
  AND token = 'pRjS6ZpAnUkHB2ZK6yuveBLFO7y6egjDDb//qAL7YYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}