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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'deb873d871aa992bfe535411b3e16ecd78871d37d888e4351e1034f96a1ba591' 
  AND token = 'ReL5hpN/1Y/s56aUzlP+sF7RWiiWzYOAcl3JcL+w+gM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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