SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '552e913cc5663763662a9e8440adc39030fa87a2e732215e7fa41a104084f174' 
  AND token = 'oCxAKNRslryhAOfHLi2qdAWfkYnUPkiCtn2W1CRvj9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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