SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37b1c0a1dff98dd6bee8f9312500d7136d37876b5911de9444193af377142839' 
  AND token = 'vBpgnhsfMfItbd7yQXVQJBM/9SUCXMisP/KQqJ2kSNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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