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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b2a28af98b36c4c04a8b2ee2a57423a0ca5d39b53d8e6bf9272bd8f85e29dd' 
  AND token = '3Fmmt2/GJs2lih0ZfXn1zrtW9fM3VukA4jCM2Dw36ME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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