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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3e4c9d6ed8781566936860507e7850cc3a04dd6a1ff4eef73878c2f0350a416' 
  AND token = 'uIN4qVrk1E8SForQ58zrAX7OAvLbmCaQ+Xt1C7SoCWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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