SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b512232bbaca439f0334abff6ab324ac27f3bd5f6507b45b04de295e2977461' 
  AND token = '+67qLiJIgsFPn7uqYcVlzwkyiwxX1LMzdq0LUQxkXe8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}