SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8b1a4c78fc792854514c98aaae08fd24c142593cfdfd88fcb12a81feca5e975' 
  AND token = 'r8KWwHG4+Xy/CmZT3TVVr86o5gohlYvjBFXA68uDpIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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