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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3b1bd6e3f9da57c6c0767a09fea2a6425af7eb8b128109ce85a0436f7a2692f' 
  AND token = 'pWUU8aD5dWepNcuTfZ+DqVjnjztzx1rKrg/VDvRCTtc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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