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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8c68f0d3701bd96310201446f9aed2fe18cc1d2aa69cead02f607a8d04afc52' 
  AND token = 'JGmRMLCF+aaOBPCZ8/lQsrJwS74NmI1RiC4sGFu/20Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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