SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84e31bc0a0652212293bdc3c13ad5cab7cfabe031f9f9fb161ca1229845bf38e' 
  AND token = 'SCx6LNm7d2SBqYW+iWaexAdpunoockybSEJcqLzosyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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