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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70dede669577565e2351ccf77a41ee69ace69e29dbb0014e24405dddf509caa6' 
  AND token = '293djKDPclFsTP+Pv6lKEjtMpSz5NcXHVGkLH61yNvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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