SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e505f3cdc5d09b4c64fad652c8d033948eb6cf83a28fe2e0133706a5e1473785' 
  AND token = 'SIeq/00RcxwSNKOMMfKy+ivBkxMC+wZ7MaOaTEMaPyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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