SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1863ed2a02ab39b9fef11948023290ffd4bdca31705bbc8da075708df8700cdb' 
  AND token = 'jhymYvw3gjyI6gxZbZNdRXFBGgjoryFZdy2XpoihTlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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