SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94cda3ad0e7c13970969180c26aa363090692c46e25b169159216c0e96dd0c33' 
  AND token = 'ZszGvYM5E3zC2SGKf1oS59XqxPox6fGA5FD96mfTsPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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