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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c4813c6d3b7ef8b5b8658c755721c4d67826237511badf87660b6029cd2d2e' 
  AND token = 'r5uGX+AH9NpBQ1V1ETtjfzrPTxDV6UUCQpBMhndW5i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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