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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4138dc0264f0d0abf91069254ec3ee5c39998500f7e91b99b8044c1ecf0b484' 
  AND token = 'DqNVmMEjzQ+aMzik3vpXri68H++OHKjoFq23mg8IPaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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