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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a7d0ca51d9b9303f92f386e2ab76798a2d1af23ee4337cd08df85d204c13ce' 
  AND token = 'Kqu5VRSeLai1UvxcAV1UFUqiEJd4ir+uBgt2ka+j5kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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