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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb3a8c0757a6a909cd9decb0b43edc574426db1699e6f65a53015de6fd4dc9ab' 
  AND token = 'rTYoiMbPMFIhQUGV+9JXtYITLp8wY9DwwvGevFrGRRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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