SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7409c3be7bf36df0f60eafe6f37af350415b71e7029e29142df49dde194aa8c' 
  AND token = 'nKlfLyXa73E2fghlJwMANeNE0Wrjrq2mUXIq2GJJgkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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