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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a34ee72264a76b75f63c423fe1c1062c6b09f0bfe5f7ac1bf236a63ba8a7e42d' 
  AND token = 'MXpwQi/GmV3gs+1yp9WGremufMuHbNcpZS1VyztK2Oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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