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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dff21fee0ff82d5e64e92f21891c65868191eddad2bced1a182c0c5a1f6fb51' 
  AND token = 'aGqL+Eb0CwJ6RgTEWs3QWLn4E3DjIPzqKsh/9zzb7vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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