SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '138bf3a862681dee702706b60fe717820ca15ae56f83adc673cc4eb4a996c998' 
  AND token = 'jyCKNUPvgRJEybXzsxHNxLHXldX4+Fyk6Ygz1zi1G3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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