SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '233a572684aa7a1e25428466e1ecfed5c776c0fba140613667db891c8e7573a3' 
  AND token = 'LKzfL9JW/VTueVLLBiunrUc330R811ZHSqV3hmkqB7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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