SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '791fcba35d0b80d1bcb51091c6ebfec3df955958f75881c031341372fe592ed4' 
  AND token = 'j5QFaRB6TT3LyDUAmZ027PggwSUt6JiTV3zVgHvInV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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