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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6cd5d5432268fc1c832d7a137cf6f66d1958ed5a021ea61195892c3eeaa0fd1' 
  AND token = 'SeX1fHYM6lrg9+RVU1c0/989AbUfvYE4V6sYb0iLHLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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