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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6a1a735cf6cb07a2bb0f5ed575c40f6b80345c6ff3b17ca8c84da763a40df38' 
  AND token = 'K4RV5RrR/7j/DYC8s3cNOzeCvq3/tGvzWkyOWHY+a9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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