SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb51b9604084677a7d59a37d054717f3f408700e90f184871b6355b75007cdf9' 
  AND token = 'o0LI7eCLi4p5Urk/KVqsG+vvc0+trDGQpOsGCXLd2Lo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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